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Date: Mon, 10 Apr 2017 16:45:51 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2 4/6] block: Quiesce old aio context
 during bdrv_set_aio_context
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To: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, qemu-block@nongnu.org, Ed Swierk <eswierk@skyportsystems.com>, Max Reitz <mreitz@redhat.com>, Eric Blake <eblake@redhat.com>

On Mon, 04/10 10:06, Kevin Wolf wrote:
> Am 08.04.2017 um 05:43 hat Fam Zheng geschrieben:
> > On Fri, 04/07 13:50, Stefan Hajnoczi wrote:
> > > On Fri, Apr 07, 2017 at 02:54:12PM +0800, Fam Zheng wrote:
> > > > @@ -4413,6 +4416,10 @@ void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context)
> > > >      aio_context_acquire(new_context);
> > > >      bdrv_attach_aio_context(bs, new_context);
> > > >      aio_context_release(new_context);
> > > > +    if (bs->job) {
> > > > +        block_job_resume(bs->job);
> > > > +    }
> > > 
> > > Should this be called before aio_context_release(new_context)?
> > 
> > Yes, and I'm going to replace it with bdrv_parent_drained_begin() as Kevin
> > suggested.
> 
> I think at the moment bdrv_parent_drained_begin() can't replace it yet,
> but you need both.

I think we have it already, see 600ac6a0e (blockjob: add devops to blockjob
backends):

    bdrv_parent_drained_begin
     -> blk_root_drained_begin
      -> block_job_drained_begin
       -> block_job_pause

Fam